Questions for NRG Energy - Keystone

 Unit Shut Downs

o Unit 2 was shut down from 9/8/12 through 11/4/12. What was the reason for the shut 

down?

o Unit 1 was shut down from 10/27/12 through 11/23/12, and then again from 11/27/12 

through 12/8/12. What was the reason for the shut downs?

o How was the FGD wastewater treatment system being operated between 10/27/2012 

and 11/4/2012, when both units at the plant were shut down? For example, please 

explain the following:

 Was newly generated wastewater being transferred to the system?

 If so, please explain from which process this wastewater was generated.

 Was the FGD wastewater treatment system operating in some type of recirculation 

mode?

 How does the flow rate through the process during this time compare to the flow 

rate during normal operation?

 What chemicals were being added to the FGD wastewater treatment system during 

this time and what were the corresponding dosages of the chemicals?

 How do the chemical dosages used during this time compare to the dosages during 

normal operation?

 Please explain any other changes regarding the operation of the FGD wastewater 

treatment system during this time.

 Why did the plant continue to discharge FGD wastewater during this period?

 Since Jan 2014, Keystone has been analyzing for arsenic and other metals using modified 200.8 

(characterized by NRG Energy as a “more sensitive analytical method”). (See Feb 21 email from 

Stephen Frank) 

o What is “modified 200.8”? Did it use a collision cell or DRC?

o Which analytes are being analyzed by 200.8?

o For what dates are 200.8 data available?

o What is RL and DL for arsenic using the 200.8?

o Are the arsenic observations detects or nondetects? What are the reported 

concentrations above the RL?
 Arsenic

o Confirm results for 7/24/12 and 8/12/13 are detects (as shown by the lab reports). 

o Why is the RL for 200.7 at 20 ug/L and not a much lower concentration? 

o What is meant by ND (“U”) for following dates which have this note: “The analyte was 

not detected at or above the listed concentration, which is below the laboratory 

quantitation limit”...but there is no concentration listed other than the DL and RL

 4/10/12, 4/11/12, 4/12/12

o Why is there a single result using EPA Method 6020 (<5 ug/L on 2/21/13)? 

 What version of 6020? 

 Was the analysis run using a collision cell or dynamic reaction cell? 

 Do the 5 dilutions suggest that an undiluted analysis would have RL of 1 ug/L?

 Why is there no lab report for the 6020 result?

o Keystone reported several J values in the data spreadsheet, but the J values do not 

appear to be reported in the lab reports:

 FGD Influent J values: 2/21/2012; 4/17/2012; 9/18/2012; 10/9/2012

 Outfall 101 J values: 6/5/2012; 6/26/2012; 7/3/2012; 7/31/2012; 9/5/2012; 

8/19/2013; 9/3/2013; 10/21/2013.

o Keystone’s data spreadsheet includes two FGD influent results on 4/10/2012; however, 

there is only one laboratory report for the FGD influent for that date. EPA did not find a 

lab report with the reported value of 1,390 ug/L for the FGD influent on 4/10/12.

o The dilution factor for arsenic at Outfall 101 for several Dec 2013 samples (12/2/2013; 

12/16/2013; 12/23/2013; 12/30/2013) were entered into the spreadsheet as 1, when 

the lab report shows 2.

 Mercury

o What is meant by ND (“U”) for following dates which have this note: “The analyte was 

not detected at or above the listed concentration, which is below the laboratory 

quantitation limit”...but there is no concentration listed other than the DL and RL

 4/10/12, 4/11/12, 4/12/12

o Why is there a “U” qualifier for 4/15/13 instead of “J”? And why is it listed as a detected 

value (no “<” in Column J)? Confirm it is nondetected (either below the RL or DL).

o 4/15/13 – Entry suggests it is a detected value because there is no “<” indicator, but the 

2500 ppt value is listed in the J-value column and the RL is 4000 ppt. Confirm this is ND.